The invention relates generally to the field of gear pumps. In particular, this invention relates to a cowling for use in existing helical gear sets for implementing a fluid pumping mechanism.
Gear pumps have been utilized to pump fluid from one area to another. In a gear pump, a pressure differential is formed at the points of convergence and divergence of the gear teeth of the intermeshing gears. If fluid is trapped between the gear teeth, the fluid will be forced out of the spaces between the gear teeth by this pressure differential.
Gear pumps typically are only used to pump fluid, and do not make up a part of the drivetrain of a vehicle. The gears used in these gear pumps are not designed to transfer larger amounts of torque, which is necessary in the drivetrain.
The gear pump concept has also been used to keep gears lubricated in a drivetrain. One such system is disclosed in U.S. Pat. No. 2,645,305. One gear in this system is partially located in a chamber of lubricant. When the gears rotate, lubricant is trapped between the gear teeth and a semi-cylindrical element. When the teeth of the gears mesh, the lubricant is forced out of the element into a chamber to provide lubrication to the bearing of one of the gears.
An innovation in gear pump systems has been to utilize some of the gears in the drivetrain, such as the gears in the transmission, to pump fluid to a location other than the bearings of the gears of the gear pump itself. One such system is disclosed in U.S. Pat. No. 3,601,515, wherein a pair of spur gears is provided with a channel element that traps fluid between the teeth of one gear and the element. The fluid travels along the element between the gear teeth to the area where the gear teeth intermesh with the teeth of the corresponding gear. At this location in the channel, an outlet port is provided, and the pressure differential forces the fluid out through the outlet port to another vehicle system.
It is desirable to further improve the pumping force provided by a gear pump utilizing drivetrain gears so as to increase the efficiency of the gear pump without adding more components or increasing package size. It is also desirable to be able to add a pumping mechanism easily to any existing helical gearset. It is also desirable to direct the pump flow in a direction parallel to the axis of rotation of the gears.
In one embodiment of the present invention, a fluid pump cowling for attachment to at least a pair of helical drivetrain gears having teeth and lands is provided. The cowling has a pair of sidewalls adapted to extend at least partially over the lands of a first of the pair of drivetrain gears and a curved sump wall extending between the sidewalls that corresponds generally to the outermost circumference of the first gear. A sump channel is defined between the sidewalls on the sump wall adjacent a distal end of the sump wall. The sump channel has a generally frustoconical shape and leads to a fluid outlet opening defined in one of the sidewalls. The cowling is positioned such that the teeth of the pair of helical gears mesh in an area in fluid communication with the sump channel to create an area of high fluid pressure upon rotational movement of the gears with a fluid.
In a second embodiment of the present invention, a fluid pump cowling for attachment to at least a pair of helical drivetrain gears is provided. The cowling comprises at least two sidewalls and an annular outer wall extending between the sidewalls. A fluid outlet opening is defined in one of the sidewalls, and a sump channel is located on an end of the outer wall. The sump channel extends between the sidewalls, and has a generally frustoconical shape. The sump channel leads to the fluid outlet opening and is tapered to a larger diameter cross-sectionally towards the fluid outlet opening.
In a third embodiment of the present invention, a method for pumping fluid using helical gears of a drivetrain is provided. The method includes the step of providing a cowling with a pair of sidewalls and an outer wall substantially matching the outermost circumference of a first helical gear. A sump channel with a generally frustoconical shape is defined on the outer wall and extends between the sidewalls. The sump channel is tapered to a larger diameter cross-sectionally towards a fluid outlet opening and has an outer wall substantially matching the outermost circumference of a second helical gear. The method includes the steps of mounting the cowling on the helical gears, immersing one of the helical gears at least partially in a fluid bath, rotating the helical gears so as to trap fluid between the teeth of one of the helical gears and the cowling, and directing the fluid into the sump channel and out of said fluid outlet opening.